Golden Valley County climate

Golden Valley County Frost Dates and Growing Season

NOAA 1991-2020 normals for Ryegate 18 Nnw, 21.3 km from Golden Valley County, elevation 4440 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ryegate 18 Nnw. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 26 and the first fall freeze around September 18, a growing season of about 112 days.

Median at 36°F
last June 13, first September 6
Median at 32°F
last May 26, first September 18
Median at 28°F
last May 11, first September 29

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FJul 3Jun 25Jun 21Jun 17Jun 13Jun 10Jun 6Jun 1May 28
32°FJun 13Jun 7Jun 2May 30May 26May 23May 20May 17May 12
28°FMay 28May 21May 17May 14May 11May 9May 6May 4May 1
24°FMay 11May 7May 4May 2Apr 30Apr 29Apr 26Apr 21Apr 17
20°FMay 3Apr 30Apr 26Apr 23Apr 19Apr 17Apr 12Apr 8Apr 4
16°FApr 28Apr 22Apr 17Apr 13Apr 9Apr 5Apr 2Mar 29Mar 22

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FAug 19Aug 27Aug 31Sep 3Sep 6Sep 9Sep 13Sep 16Sep 21
32°FSep 1Sep 7Sep 11Sep 15Sep 18Sep 21Sep 24Sep 27Oct 1
28°FSep 14Sep 20Sep 24Sep 26Sep 29Oct 1Oct 4Oct 7Oct 12
24°FSep 22Sep 28Oct 1Oct 4Oct 7Oct 11Oct 14Oct 17Oct 23
20°FOct 1Oct 4Oct 8Oct 12Oct 16Oct 19Oct 23Oct 27Nov 1
16°FOct 6Oct 12Oct 17Oct 20Oct 24Oct 28Nov 1Nov 4Nov 9

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F1049892888379746859
32°F1331261211161121071029790
28°F157150146142139134130125117
24°F178172167163159156152147140
20°F200193188183179175169164157
16°F222213208203198193188183174

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
8,074
Cooling degree days, base 65°F
259
Growing degree days, base 40°F
3,473
Growing degree days, base 45°F
2,509
Growing degree days, base 50°F
1,711
Growing degree days, base 55°F
1,072
Growing degree days, base 60°F
588

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27700
February1,11001
March97804
April713022
May4562110
June21120272
July57113521
August76103496
September28420229
October663152
November98404
December1,26600

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 21.3 km from Golden Valley County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00247263 (Ryegate 18 Nnw). Public domain.